The Bouygues Murphy joint venture delivering the Lower Thames Crossing is seeking a single large tunnel boring machine (TBM) to excavate both the northbound and southbound tunnels. This approach is intended to help control costs on a scheme currently projected at £11bn.
According to the project team, tunnel excavation is scheduled to begin in 2028. Ahead of this, construction of the northern tunnel entrance is due to start in the coming summer, including a 26m-deep launch chamber.
The launch chamber will also accommodate a temporary segment factory to produce the precast concrete lining for the tunnel. The lining is being designed to withstand 6.5 bar of pressure from the Thames Estuary.
The Lower Thames Crossing is described as set to be one of the widest road tunnels in the world and, at 110m long, the UK’s longest road tunnel. These claims are attributed to the project’s promoters and have not been independently verified in this report.
Roads and buses minister Simon Lightwood said the launch of procurement for one of Europe’s largest tunnelling machines marks a major step forward for the project, which has been allocated £891m in the Budget. He said the crossing is expected to relieve congestion at Dartford, improve connectivity between ports, manufacturing centres and communities, and act as a driver of jobs and growth.
Development consent for the Lower Thames Crossing was granted in March this year, following a protracted approvals process since the scheme was first proposed in 2009. The route is intended to relieve the Dartford Crossing by linking the A2 in Kent with the M25 in Essex, although it has faced opposition from environmental groups and regulatory challenges.
At the time of approval, National Highways’ Lower Thames Crossing executive director Matt Palmer said the project aims to set a new standard for major schemes focused on a net-zero future, including scaling up low‑carbon construction methods and leaving a legacy of green spaces and skills. He added that plans had been shaped by local consultation and independent examination, and that the team is ready to move into detailed planning and construction once funding arrangements are confirmed.
